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  1. #1
    JeffD's Avatar
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    Couple of large format close up exposure questions

    I am setting up some still lifes that will be about 1:1 very close up.

    When I meter the scene, should I meter from where the lens is, or where the film plane is? Normally, I wouldn't care, but shooting this close I am not sure.

    Also, is there some kind of calculator available online, that would let me punch in my lens focal length, what my bellows length is, and then tell me my additional exposure to add?

    Lastly, when measuring bellows length for something like this, would I measure from the diaphram opening of my shutter to the film plane, or the rear of the lens glass to film plane, or some other distance?

    Thanks for any comments.

  2. #2
    David H. Bebbington's Avatar
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    Meter the subject normally (from where the lens is). Measure bellows extension from the lens diaphragm. For exposure correction, try this (from "The Manual Of Photography", pub. Focal Press):
    Last edited by David H. Bebbington; 07-23-2007 at 04:17 AM. Click to view previous post history.

  3. #3

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    Quote Originally Posted by JeffD
    I am setting up some still lifes that will be about 1:1 very close up.

    When I meter the scene, should I meter from where the lens is, or where the film plane is? Normally, I wouldn't care, but shooting this close I am not sure.

    Also, is there some kind of calculator available online, that would let me punch in my lens focal length, what my bellows length is, and then tell me my additional exposure to add?

    Lastly, when measuring bellows length for something like this, would I measure from the diaphram opening of my shutter to the film plane, or the rear of the lens glass to film plane, or some other distance?

    Thanks for any comments.
    To answer your questions as you posed them:

    You would normally meter the object you are photographing.

    I don't know of an online calculator. I use the calculator in the Kodak Professional Photoguide I purchased over twenty years ago. I don't know if it is still available. If I want to do a quick and dirty calculation, I will take the focal length of the lens and convert to inches and the bellows extension in inches from the film plane to the lens and arrive at the corrected effective Fstop. In other words if I have a 210 mm lens (8 inch) and my bellows extension is 16 inches then the correct Fstop for exposure calculation will be F 16.

    When I check this in the Kodak Photoguide, it tells me a correction factor of 4 which is the same (2 stops). The magnification is 1 to 1.

    I measure from the film plane to the shutter. It serves the purposes.

    Good luck.

  4. #4

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    I tried this when Donald mentioned it before, and it worked good enough fo transparencys.

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    You can do the arithmetic in your head. Magnification = (extension/focal length) - 1. I measure extension with a tape measure, from back of camera to diaphragm. Not quite correct, close enough. Exposure compensation, in stops, = magnification + 1.

    Stops run f/1, f/1.4, f/2, ... Everyone knows the sequence. Shutter speeds run 1, 1/2, 1/4, ... Everyone knows the sequence. Both sequences are engraved on the shutter and on the light meter. One stop compensation means, use next larger aperture (e.g., f/16, not f/22) or next slower shutter speed (e.g., 1/30, not 1/60).

  6. #6
    morkolv's Avatar
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    For bellows extension I use the Quick-disc, its very fast, built-in focal length adjustments, and it Free!! See here QuickDisc
    Morten :-)


    "Please ! Bring me into the company of those who seek the truth, and deliver me from those who have found it."

  7. #7
    Chazzy's Avatar
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    Just to be sure I understand the application of this, if I am exposing 4x5 film and the subject area is 8x10, I only need to increase the exposure by one stop?

  8. #8
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    Quote Originally Posted by JeffD
    I am setting up some still lifes that will be about 1:1 very close up.

    When I meter the scene, should I meter from where the lens is, or where the film plane is? Normally, I wouldn't care, but shooting this close I am not sure.

    Also, is there some kind of calculator available online, that would let me punch in my lens focal length, what my bellows length is, and then tell me my additional exposure to add?

    Lastly, when measuring bellows length for something like this, would I measure from the diaphram opening of my shutter to the film plane, or the rear of the lens glass to film plane, or some other distance?
    Meter the scene with an incident meter at the subject.

    I carry a metric ruler and a pocket calculator in my camera case, and use them to calculate the exposure factor. I measure from the diaphragm of the lens to the film plane, divide that by the focal length, and square the result. The formula is: (LF/FL)squared. This will give you an exposure increase factor. For example, say you have a 180 mm lens, and your lens to film distance is 360mm. 360/180=2; 2 squared is 4. You need four times the exposure, or two stops. This saves you from having to calculate magnification.
    You can punch it in and get the answer faster than you can read this.

  9. #9
    JeffD's Avatar
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    Thanks everyone for the answers! This helps me a lot, and will save me some incorrectly exposed film.

    Eddym: That calculation works for me- pretty simple to remember. How come you use an incident meter? Any particular reason?

    Morkolv: I tried the quick disk- the only problem is that it seems like I can never actually place the disc in my scene where I can "measure" it on the ground glass. For instance, currently I am doing a close up of a flower, which is in a vase. There is really no way to have the disc in the scene without an assistant holding it

  10. #10
    Bob F.'s Avatar
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    Quote Originally Posted by JeffD
    Morkolv: I tried the quick disk- the only problem is that it seems like I can never actually place the disc in my scene where I can "measure" it on the ground glass. For instance, currently I am doing a close up of a flower, which is in a vase. There is really no way to have the disc in the scene without an assistant holding it
    I'm not exactly the world's most experienced but I have found that Blue-Tak is often my friend in these situations - or the disc can be popped in amongst the leaves etc. The beauty is that it does not have to be face-on to the camera: it can be at any angle; you just measure it along it's longest axis on the gg screen.

    Have fun, Bob.

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